1. Field of the Invention
The present invention relates to a sliding device for use with a machine tool, a measuring device or the like, and more particularly to an improvement of a bearing unit which is used in the sliding device.
2. Description of the Prior Art
In the prior art sliding device, there is shown a ball bearing unit for linear motion wherein said slide unit is mounted on a track rail of rectangular cross section which is provided with linear track surfaces symmetrically at both vertical side surfaces. The slide unit is provided with track surfaces opposing said track surfaces on said track rail with linear return holes running parallel to said track surfaces . Direction changing paths connect corresponding ends of said track surfaces and return holes respectively. The slide unit is further formed with circulating paths where groups of balls endlessly circulate and support a load while rolling between both track surfaces.
In the prior art ball bearing unit, a load is supported by many numbers of balls which are rotatably inserted into the circulating paths having circular cross sections. According to the prior art ball bearing unit, there will occur friction between inner surfaces of the circulating paths and the balls. Moreover, each of the balls contacts the inner wall of the circulating path. Accordingly, there were defects in that the load capacity of the slide unit was decreased and in that the inner surface of the circulating path was damaged. Moreover, there were defects in that there would occur the collision of adjacent balls, since each of the balls is rotatably provided in the circulating path individually and in that it was very difficult to obtain high precision manufacturing of the circulating path.